Based on what I've heard Terry say, and other's experiences reported on this site (and mine, too)...he's not had any trouble mating tanks/bowls made in different countries with Toto. And, the colors match, too. That's what I was saying about QA/QC...they have it. Toto does make a bunch of toilets in Georgia, but depending on sales, weather, shipping, and probably other things, they bring supplies in from where ever they need to to try to meet demands. Most of their toilets that use the Unifit adapter are made here (at least for the US consumption), and some other models, but it's not a certainty you'll get one made in the USA. One of the big things with any porcelain product is the amount it shrinks from when cast to once dried and then fired. Most companies pour their slip into the molds...Toto uses a much drier mix and almost packs it in. Starting out with less moisture means it has less chance to slump and shrinks less. This keeps things like trapways the design shape and helps things stay nice and flat and level. Nothing's perfect, but their technique works.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014